1. Field of the Invention
This invention relates to a cis-element inducible in response to injury and derived from a promoter region of FAD7 of Arabidopsis thaliana Heynh.
2. Description of Related Art
Studies have confirmed the significant relationship between cold-resistance of a plant and the degree of unsaturation of fatty acids constructing biomembrane thereof. The inventors have experimentally indicated that a transformed-tobacco plant acquires higher-resistance against low temperatures by expressing a fatty acid desaturase, (unsaturating enzyme) gene FAD7, derived from Arabidopsis thaliana, in a high degree in the plant.
On the other hand, to produce certain protein in plant cells, a promoter, which exhibits constitutive expression and strong promoter activity, have been used. Such a promoter functions regardless of its external environmental conditions, sometimes providing economical losses in breeding a plant. For example, to improve the resistance of a plant against physical environmental stresses such insect damage, the use of various genes with resistant properties to the stresses is now investigated. That is, the resistance against injury might be improved by expressing xcfx89-3 fatty acid desaturase enzyme by means of its constitutive promoter functioning in response to insect damage or physical damage.
Such particular expressed protein, however, is unnecessary for a plant under normal condition without injury. However, in the conventional gene expression system using a constitutive promoter, a plant is forced to express a particular protein, such as xcfx89-3 fatty acid desaturase enzyme, unnecessary under normal condition.
Based on such background, it has been demanded to develop a promoter inducible in response to injury. For example, it is required to produce a breeding intermediate mother body, wherein the expression of a gene, which encodes xcfx89-3 fatty acid desaturase enzyme or other proteins contributing to improving resistance of a plant against insect damage, may be induced in response to injury.
An object of the invention is to provide an element inducible in response to injury, which may be added to a promoter for developing a promoter inducible in response to injury.
Another object of the invention is to provide a means for developing a breed intermediate mother body with improved resistance against injury, by using a promoter provided with such element inducible in response to injury.
The invention provides an element inducible in response to injury, the element comprising
(a) a base sequence referred to as nucleotide numbers from xe2x88x92430 to xe2x88x92363 in a sequence number 1 in a sequence list, or
(b) a base sequence hybridizes with the base sequence (a) under stringent condition, the base sequence (b) being inducible in response to injury, or
(b)xe2x80x2 a base sequence (a), a part of which is deleted or substituted by another base sequence, or to which another base sequence is added, the base sequence (b)xe2x80x2 being inducible in response to injury.
The invention provides an element inducible in response to injury, the element comprising
(c) a base sequence referred to as nucleotide numbers from xe2x88x92242 to xe2x88x92223 in a sequence number 1 in a sequence list, or
(d) a base sequence (d) hybridizes with the base sequence (c) under stringent condition, the base sequence (d) being inducible in response to injury, or
(d)xe2x80x2 a base sequence (c), a part of which is deleted or substituted by another base sequence, or to which another base sequence is added, the base sequence (d)xe2x80x2 being inducible in response to injury.
The invention also provides an injury-inducible promoter characterized by containing each of the elements described above, and a transgenic plant comprising a recombinant DNA containing this injury-inductible promoter.
An xcfx89-3 fatty acid desaturase enzyme catalyzes the final step of production of triene-fatty acids in a plant, which are main components of plant lipids. FAD7 derived from Arabidopsis thaliana is a gene encoding xcfx89-3 fatty acid desaturase enzyme localized in chloroplast. FAD7 is specifically expressed in chloroplast organs and its expression is shown to be light-inducible.
Moreover, it is shown that localized damage on a plant body causes highly expression of FAD7, not only in chloroplast organs but also in non-chloroplast organs such as stalk or root. The invention identified a cis-element, in a promoter region of FAD7 gene, involved in organ-specific induction in response to injury, and therefore has an inventive step.